Low-torque choke valve for well automation

ABSTRACT

A choke valve body of a valve apparatus includes a lower stem that terminating at a lower end thereof with a plug. A conduit traverses a lower portion of the lower stem between at least one plug aperture traversing the plug to at least one top aperture traversing an upper end of the lower portion. The lower portion is slidably retained within the valve chamber between closed and open positions. A bonnet fixed with the valve body has a bonnet chamber for receiving the lower portion, and a bore with at least one annular seal for slidably retaining an upper portion. A yoke assembly is fixed with the bonnet, terminates at an upper end with a drive mechanism, and includes an upper stem with a threaded upper end that is driven between raised and lowered positions by the drive mechanism, the upper stem fixed with the lower stem.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication 61/936,300, filed on Feb. 5, 2014, and incorporated hereinby reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

Not Applicable.

FIELD OF THE INVENTION

This invention relates to remote controlled actuated choke valves, andmore particularly to an improved valve requiring very low operatingtorque or force, requiring less electric power consumption, and thussuitable to be automated by SCADA, RTU with HMI systems used in oil andgas well production.

DISCUSSION OF RELATED ART

Prior art choke valves, such as that taught in U.S. Pat. No. 5,706,856to Lancaster on Jan. 13, 1998 and other prior art devices, particularlyon fluid lines having 15,000 psi or greater, often have a relativelyhigh torque requirement to open and close such valves, resulting in moreenergy demand and power consumption for remote, relatively largemotorized actuators such as those found on motorized actuated chokes.This is due primarily to lack of pressure balance between both sides ofthe choke and a relatively high seal friction (see FIG. 6 of Lancaster).Such choke valves for use in product wells or oil and gasolinefacilities result in higher operating costs.

Remote operation of new art choke valves of for oil productionfacilities, for example, results in low operating costs. However, priorart valves, particularly on fluid lines having 15,000 psi or greater,often have a relatively high torque requirement to open and close suchchoke valves, resulting in more energy demand for remote, motorizedactuators. Such actuators typically have a high power requirement andcannot be easily set-up at remote locations far from utilities.

Further, prior art choke valves typically have multiple rubber seals(see FIG. 3 of Lancaster) that are susceptible to damage in oilproducing and fracking operations due to high concentrations of CO₂,H₂S, and sand in many of the fluid flows resulting from such operations.Moreover, such prior art valves have a relatively large number of sealscontained in seal-cartridges that are difficult to remove from thebonnet due to the corrosive impact of sour gas and carbonic productionfluids produced in oil and gas operations. Of the entire bonnet must bereplaced when servicing such valves, which is a costly repair. Further,such prior art choke valves have seals that have little sealing value,but must still be maintained and serviced, which further increases sealfriction and operating torque.

Therefore, there is a need for a choke valve apparatus that greatlyreduces the torque or force required for the opening and closing of thevalve, even with line pressures as high as 20,000 psi, through as highas a 98% pressure balance on either side of a valve plug. Such a neededinvention would allow the use of relatively small electric actuatorsthat have low current and power consumption to operate, and that can beoperated even with a relatively low-cost solar cell and battery system,thereby not requiring access to an electrical utility. Such a neededproduct would allow operating with low-cost SCADA systems, for example.Regardless of the fluid inlet or outlet pipe size, from 1″ to 6″, thetorque required to open and close such a needed valve would remainrelatively low.

Moreover, such a needed invention would have as few as one seal locatedbelow an easily-accessed seal packing gland to simplify maintenance andreplacement of the seal. Such a needed apparatus would have very littlefriction between a yoke and an upper and lower stems that is common withprior art products. Moreover, such a needed invention would be easilyadapted to a variety of different styles of choke valves, namely oil andgas industry choke-type valve standards such as H2, JWA, OCT style, Flowback, VG1000, Extended Bolt, Studded, Inline, Stepper, Hydraulic,Drilling chokes and valves, and the like. Still further, such a neededinvention can be optionally utilized without elastomer O-rings or otherrubber parts that are subject to damage by caustic chemicals commonlyfound in oil and gas production systems.

Prior art devices and also Lancaster type choke valves also have arelatively complicated indicator drive assembly situated in non-machinedrough surfaces of the yoke or rectangular tubing (see Lancaster FIGS. 1,5 and 6). Such prior art indicator drive assemblies include a fabricatedsleeve held in place with plastic buttons and pins that slide throughthe non-machined rough surface of the yoke, resulting often in misreadindicator readings. Field service and replacement of such indicators isdifficult since the indicator mechanism is a part of the fixedconnection of both the lower and upper stems and the assembly guide, andsince it is locked by two large tapered nuts located at the upper andlower end of the tubing.

Such prior art devices provide no means of overload protection fromhigher motor drive torque due to use of fixed joints between the upperand lower stems (see FIGS. 1 and 5 of Lancaster). Particularly when thevalve is closed against full differential pressure acting on the seat,relatively high torque is required to unseat the stem from the seat,since there is zero pressure at the outlet and full working pressure atthe inlet. Often such high torque requirement to open the choke valveincreases the actuator motor's current capacity, thus damaging orburning out the motor, and causes thread damage upper and lower stemsincluding the drive shaft assembly and coupling, which results arelatively high cost of repair and significant down time.

Prior art valves, such as the Lancaster-type choke valve, use anunthreaded choke seat. Just to retain and hold the choke seat in thebody and seal it, the prior art Choke valve uses three parts: 1) seatretainer, 2) bonnet, and 3) internal threaded wing nut inside the chokebody (refer to FIG. 1 of Lancaster). These three parts and the lowerstem reduce volume within the body cavity and result in greater fluidturbulence, wear and tear within the body and the internal parts, whichfurther increases required torque to move the valve as well asadditional wear and tear on the internal components of such devices.Further, such valves often result in the choke seat getting stuck intothe chock body cavity due to corrosive activity at the seating area. Assuch a valve seat utilizes an elastomer rubber seal, often such seal isworn prematurely and are destroyed internally. A stuck choke seat insuch a choke body can only be removed by attempting to pull the seat outof the corroded body outlet area, requiring in some instances that thechoke body has to be removed from the well just to push the choke seatout from the outlet of the body. As such, prior art valves of this typeare often costly to service in the field and expensive to manufactureand assemble in the first place.

Lancaster and other prior art devices have further drawback that asingle tubing structure holds the bonnet and upper hardware assembly,the indicator drive assembly and the upper and lower stems with a fixedcoupling (see Lancaster FIGS. 1 and 5). Such a one-piece design makesassembly, disassembly, and servicing complicated due to the difficultyof aligning the drive shaft, upper stem and lower stems. Further, such adevice results in the need for additional bearings and results ingreater rotational friction. Large tapered nuts at both ends of suchtubing assembly are difficult to assemble, disassemble and service.

Moreover, the manual override assembly of the prior art devices requiresa complicated handle and drive assembly to facilitate manual override ofthe valve (refer to Lancaster FIG. 4). The present inventionaccomplishes these objectives and overcomes the drawbacks of the priorart.

SUMMARY OF THE INVENTION

The present device is a dual functional manual and actuated choke valvesystem for controlling the flow of fluid, such as a high-pressurehydrocarbon stream, between a source and a receiver. The valve is apressure-balanced choke valve used for high pressure fluids and actuatedwith an electric actuator and controller, monitored and operated throughautomated systems such as remote HMI, RTU, or SCADA-type systems, forexample. A choke valve body has a valve chamber with an inlet and anoutlet. A seat is disposed within the valve chamber.

A lower stem has an upper portion and a lower portion. The lower portionhas an upper end and a lower end and terminates at the lower end thereofwith a choke trim, such as a conical choke-type plug, a cylindricalgate-type plug, or the like. A conduit traverses the lower portion ofthe lower stem between at least one plug tip aperture traversing theplug to at least one top aperture traversing the upper end of the lowerportion of the lower stem.

The lower portion of the lower stem is slidably retained at leastpartially within the valve body chamber between a closed position and anopen position. In the closed position the plug tip abuts the seat orcloses vertical slots of the seat or occludes vertical slots of theseat, to prevent fluid flow between the inlet and the outlet. In theopen position the plug-tip is axially retracted from the seat to permitfluid flow between the inlet and the outlet.

A bonnet is selectively fixed with the valve body and has a bonnetchamber axially aligned with the lower portion of the lower stem forreceiving the lower portion at least partially and slidably therein. Thebonnet includes a bore that is axially aligned with the lower portion ofthe lower stem and includes at least one annular seal or bushing.Preferably the bonnet is selectively fixed with a threaded portion ofthe valve body at a metal-to-metal seal by a wing/bonnet nut. Themetal-to-metal seal prevents the fluid from leaking between the valvebody and the bonnet when the wing nut is tightened.

The upper portion of the lower stem is axially aligned with and fixed ata lower end thereof with the upper end of the lower portion. The upperportion of the lower stem is axially retained within the bore of thebonnet and the annular seal. The diameter of the upper portion is therelative smaller than the diameter of lower portion. This diameterremains constant; regardless the orifice sizes 1″, 2″ up to 6″ or largerorifice of the choke valves to achieve lowest operating torque.

A yoke assembly is selectively divided into two distinguished parts: 1)support plate and 2) U-back. The support plate connects with the upperportion of the bonnet and terminates at a lower end of the U-back with arotational drive mechanism. The U-Back assembly includes an upper stemthat is axially aligned with the lower stem and has a threaded upperend, axially aligned with the drive shaft. The lower end of the upperstem is part of a breakaway stem coupling or fixed coupling that iscoupled with the upper end of the upper portion of the lower stem.Design of the yoke assembly in two parts provides the ability toaccommodate high pressure wetted area separating the upper drivemechanism and the electric actuator, thus making the total assemblyeasier to manufacture, hydro test, field service, maintain, and thelike.

Further the present invention includes a simplified indicator designthat is embedded in a polished indicator housing-sleeve tightly attachedto the upper stem. Such an indicator design is simpler and follows aclassic pattern that is well recognized in the industry and more easilyread.

The middle portion of the upper stem is equipped with a rotary indicatorhousing-sleeve containing an indicator drum, meter marked on thecircumference with up to 64^(th) of diameter, representing the choketrim opening for the orifice diameter, preferably in inches. Theindicator is externally attached to the drive shaft. The linear up anddown movement of the upper and lower stems and indicator housingindicates the diametrical opening of the choke trim. Such an indicatormay be made from a wide variety of the materials such PVC, Delrin,Aluminum, stainless steel and the like. A shoulder bolt passing throughthe vertical slot in the U-Back connects at another end into theindicator housing. Operation of the choke valve results in up and downmovement of the shoulder bolt converting the rotational motion of thedrive shaft to a linear motion of the upper stem coupled with upperportion of the lower stem. An internally-threaded rotational drive shaftcaptures up and down motion of the threaded upper end of the upper stembetween a raised position with shoulder bolt that corresponds with theopen position of the stem tip (plug) and choke valve apparatus, and alsoa lowered position corresponding to the closed position of the choketrim and choke valve apparatus.

Preferably the upper end of the U-Back assembly is selectively fixedwith bottom side of the thrust housing. The U-back assembly may furtherinclude having at least one slot therein aligned with the upper andlower stems. The at least one slot is adapted for slidably capturing theshoulder bolt therein that transversely engages with the upper and lowerstems, to prevent rotation of the upper and lower stems, by the driveshaft. The rotational drive mechanism further preferably includes athrust assembly, disposed about the drive shaft that includes at leastone thrust bearing each end of it, to prevent axial movement of thedrive shaft while facilitating rotational movement of the drive shaft.The drive shaft may terminate at a top end thereof with a hex coupling,such that a handle wrench or wheel may be used to manually rotate thenut to move the valve apparatus between the closed and open positions.

Preferably the yoke assembly is selectively fixed with a top side of thebonnet at a yoke support plate of the bonnet. The yoke assembly mayfurther include a yoke having at least one slot therein aligned with theupper and lower stems. The at least one slot is adapted for slidablycapturing a shoulder bolt therein that transversely engages with theupper and lower stems, to prevent rotation of the upper and lower stemsby a drive stem or shaft.

The rotational drive mechanism further preferably includes a thrustassembly disposed about the drive shaft that includes at least onethrust bearing to prevent axial movement of the drive shaft whilefacilitating rotational movement of the drive shaft. The drive shaft mayterminate at a top end thereof with a nut or hex coupling, such that ahandle wrench or wheel may be used to manually rotate the nut to movethe valve apparatus between the closed and open positions. Alternately,the drive shaft terminates at an actuator coupling, such that anelectrically-driven valve actuator engaged with the actuator couplingmay be used to remotely move the valve apparatus between the closed andopen positions.

In use, the bonnet chamber at the lower end of the upper portion of thelower stem is always in fluid communication with the inlet through theat least one top aperture of the upper end of the lower portion of thelower stem, the conduit, and the at least one plug aperture of the plug,such that the fluid pressure at the upper portion of the lower stem issubstantially equal to the fluid pressure at the inlet. As such, theannular seal prevents the fluid from leaking between the upper portionof the lower stem and the bore of the bonnet. Further, but pressure ofthe at least one annular seal against the lower stem accounts for mostof the friction that must be overcome for the rotational drive mechanismto move the plug between the open and closed positions.

The present invention is a valve apparatus that greatly reduces thetorque or force required for the opening and closing of the valve, evenwith line pressures as high as 20,000 psi, through as high as a 98%pressure balance on either side of the valve plug. The present deviceallows for the use of relatively small electric actuators that have lowcurrent and power consumption to operate, as low as 1.0 amp. As such,the present invention can be operated even with a relatively low-costsolar cell and battery system, thereby not requiring access to anelectrical utility, such as a remote HMI, RTU, or SCADA-type systems,for example. Regardless of the fluid pipe size, from 1″ to 8″, thetorque required to open and close a valve of the present inventionremains relatively low and thereby more suitable for automated systems.An entire field of 50 or more wellheads may be automated, for example,with the present system, greatly reducing the cost of fields requiringelectric lines run to each valve for higher-voltage actuators.

Moreover, the present device has as few as one seal located behind aneasily-accessed seal and lubrication packing plug to simplifymaintenance and replacement of the seal, without require completedisassembly of the yoke and/or valve. The present device results in aminimum of friction between a yoke and an upper stem, and the lower stemand the seals, that is common with prior art products. In the presentdevice, the seal is located in a packing gland away from the bonnetpressure chamber for ease of accessibility, resulting in more efficientsealing with a minimum of friction between the yoke and the lower stem.Moreover, the present device is easily adapted to a variety of differentstyles of valves and chokes, namely oil and gas industry standards suchas H2, JWA, OCT, Flow back, AGC, Extended Bolt, In Line or Angled,Studded, Bolted, Winged, Stepper or Linear, Manifold, Drilling, AG1000and the like. Still further, the present invention can be optionallyutilized without elastomeric seals or other rubber parts that aresubject to damage by caustic chemicals commonly found in oil and gasproduction systems, both on land and at sea.

Further, the present invention includes a simplified indicator designthat is embedded in the polished sleeve, tightly attached to the upperstem. Such an indicator design is a more simple and classic indicatordesign that is well recognized in the industry, and more easily read.Such an indicator may be made from a wide variety of suitable materialssuch as PVC, Delrin, Aluminum, stainless steel, or the like, allowingcalibration down to 64^(th) diameter, unit percentage or millimeterlinear travel distances with little error. Using two pieces of U-backtubing allows the chock body to be separated from the indicator andmotor drive assembly.

The breakaway actuator or stem coupling of the present inventiondisconnects the choke valve from the actuator motor between the upperand lower stems in the present device in the event of an over-torquesituation, such as while attempting to move the valve from one positionto the other when the valve is stuck. The threaded seat of the presentinvention that includes a metal-to-metal seal between the inlet andoutlet results in greater valve cavity volume, less fluid turbulencetherein during use, greater reliability and lower cost servicing.Further, the two-piece yoke design of the present invention allows foreasy separation of the actuator from the choke by simply removing thecoupling held by bolts and nuts. As a result, the pressure seal situatedunder the packing gland may be readily replaced, and the chock trim(lower stem and seat) can be easily changed within a short time withoutaffecting the electrical actuator connection and the upper hardwareassembly.

The present invention further includes a relatively simple handle formanually overriding the actuator of the valve. Such a handle may bereadily detached when not in use, and includes relatively few parts.Other features and advantages of the present invention will becomeapparent from the following more detailed description, taken inconjunction with the accompanying drawings, which illustrate, by way ofexample, the principles of the invention.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional diagram of a valve apparatus of the presentinvention, illustrated in a closed position;

FIG. 2 is a cross-sectional diagram of a valve apparatus of the presentinvention, illustrated in an open position;

FIG. 3 is a partial perspective view, partially cut-away, of a valveapparatus of the present invention, illustrating an alternate choke-typevalve plug;

FIG. 4 is an enlarged, partial cross-sectional view of FIG. 2,illustrating a valve body;

FIG. 5 is an enlarged, partial cross-sectional view of FIG. 2,illustrating a bonnet and a portion of a yoke assembly;

FIG. 6 is a partial perspective view, partially cut-away, of FIG. 2,illustrating the yoke assembly;

FIG. 7 is an enlarged, partial cross-sectional view of FIG. 2,illustrating the yoke assembly and a thrust assembly;

FIG. 8 is a cross-sectional view of a breakaway coupling of theinvention;

FIG. 9 is a front elevational view of an indicator of the invention; and

FIG. 10 is a flow diagram of the actuated choke of the present inventionused for well automation

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrative embodiments of the invention are described below. Thefollowing explanation provides specific details for a thoroughunderstanding of and enabling description for these embodiments. Oneskilled in the art will understand that the invention may be practicedwithout such details. In other instances, well-known structures andfunctions have not been shown or described in detail to avoidunnecessarily obscuring the description of the embodiments.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” Words using the singular or pluralnumber also include the plural or singular number respectively.Additionally, the words “herein,” “above,” “below” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Whenthe claims use the word “or” in reference to a list of two or moreitems, that word covers all of the following interpretations of theword: any of the items in the list, all of the items in the list and anycombination of the items in the list. When the word “each” is used torefer to an element that was previously introduced as being at least onein number, the word “each” does not necessarily imply a plurality of theelements, but can also mean a singular element.

FIGS. 1 and 2 illustrate a valve apparatus 10 for controlling the flowof fluid, such as a high-pressure hydrocarbon stream, between a source18 and a receiver 19. The source 18 may be an oil well, for example, andthe receiver 19 may be a storage tank (not shown), or the like.

A rigid, metallic valve body 20 has a valve chamber 30 with an inlet 28and an outlet 29. In one embodiment, the valve chamber 30 includes ableed aperture 440 and a bleed nut 430 that is threadably engaged withthe bleed aperture 440, such that the valve chamber 30 may be drained atthe bleed aperture 440. The valve body 20 is preferably made with ahardened steel or iron material.

A seat 40 is disposed within the valve chamber 30, preferably with athreaded, metal-to-metal seal 270 (FIGS. 2 and 3). The seat 40 ispreferably made from a relatively hard material, such as a carbidematerial embedded in a jacket made from materials such as nickel basedalloy or chrome base alloy such as stainless steel.

A lower stem 50 has an upper portion 60 and a lower portion 70. Thelower portion 70 has an upper end 78 and a lower end 72 and terminatesat the lower end 72 thereof with a plug 80. In one embodiment, the plug80 is a conical choke-type plug 240 (FIG. 3). Alternately the plug 80may be a generally cylindrical gate-type plug 250 (FIGS. 1, 2 and 4).Preferably the plug 80, like the seat 40, is made from a relatively hardcarbide material, stainless steel or nickel materials with a silversoldered carbide tip, or other suitably hard, strong and durablematerial. A conduit 90 traverses the lower portion 70 of the lower stem50 between at least one plug aperture 100 traversing the plug 80 to atleast one top aperture 110 traversing the upper end 78 of the lowerportion 70 of the lower stem 50 (FIGS. 3-5).

The lower portion 70 is slidably retained at least partially within thevalve chamber 30 between a closed position 120 and an open position 130.In the closed position 120 the plug 80 abuts the seat 40 to preventfluid flow between the inlet 28 and the outlet 29. In the open position130 the plug 80 is axially retracted from the seat 40 to permit fluidflow between the inlet 28 and the outlet 29. In one embodiment, thelower portion 70 of the lower stem 50 is axially maintained within thevalve chamber 30 with at least one annular U-ring 260 situated betweenthe at least one top aperture 110 and the at least one plug aperture100.

A bonnet 140 is selectively fixed with the valve body 20 and has abonnet chamber 150 axially aligned with the lower portion 70 of thelower stem 50 for receiving the lower portion 70 at least partially andslidably therein. The bonnet 140 includes a bore 160 that is axiallyaligned with the lower portion 70 and includes at least one annular seal170.

Preferably the bonnet 140 is selectively fixed with a threaded portion146 of the valve body 20 at a metal-to-metal seal 270 by a wing nut 280(FIGS. 1-4). The metal-to-metal seal prevents the fluid from leakingbetween the valve body 20 and the bonnet 140 when the wing nut 280 istightened. In one preferred embodiment, the bore 160 of the bonnet 140further includes a threaded, annular packing nut 290 (FIGS. 1, 2, 5 and6) through which the upper portion 60 of the lower stem 50 is slidablyretained. The bore 160 includes a packing nut thread 165 for engagingthe packing nut 290, such that the annular seal 170 may be accessed anlubricated from outside of the bonnet 140 by removing the packing nut290.

The upper portion 60 of the lower stem 50 is axially aligned with andfixed at a lower end 62 thereof with the upper end 78 of the lowerportion 70. The upper portion 60 is slidably retained within the bore160 of the bonnet 140 and the annular seal 170. The diameter D_(u) ofthe upper portion 60 is at most one-half of the diameter D_(l) of thelower portion 70.

A yoke assembly 180 is selectively fixed at a lower end 182 thereof withthe bonnet 140 and terminates at an upper end 188 thereof with arotational drive mechanism 190. The yoke assembly 180 includes an upperstem 200 that is axially aligned with the lower stem 50 and has athreaded upper end 208 and a lower end 202 that is fixed with the upperend 68 of the upper portion 60 of the lower stem 50, preferably at abreakaway coupler 420 (FIG. 8). The rotational drive mechanism 190includes an internally-threaded rotational drive shaft 210 that capturesand drives the threaded upper end 208 of the upper stem 200 between araised position 230 that corresponds with the open position 130 of theplug 80, and a lowered position 220 corresponding to the closed position120 of the plug 80.

The breakaway coupler 420 includes a frictional threaded sleeve 421 thatslides out from the coupling 420 with the lower stem 50 when a torquelimit threshold is reached. The upper stem 200 thereafter experiences asubstantially zero load, preventing damage to the valve actuator 410.Further, the threads on both the upper and lower stems 200,50 are notdamaged. Replacement of the coupling 420 is accomplished by reducingfluid flow to the valve apparatus 10, and the coupling 420 is theneasily replaced.

Preferably the yoke assembly 180 is selectively fixed with a top side148 of the bonnet 140 at a yoke support plate 300 (FIG. 9) of the bonnet140. The yoke assembly 180 may further include a yoke 310, or U-back,having at least one slot 315 therein aligned with the upper and lowerstems 50,200. The at least one slot 315 is adapted for slidablycapturing a shoulder bolt 320 therein that transversely engages with theupper and lower stems 50,200 to prevent rotation of the upper and lowerstems 50,200 by the drive shaft 210, whereby rotary motion is convertedto linear motion.

In one embodiment the yoke assembly 180 further includes an outerindicator sleeve 330 fixed with the upper stem 200 and an innerindicator 340 fixed with the yoke assembly 180 and within the indicatorsleeve 330 (FIGS. 3, 6 and 9). As such, as the upper stem 200 moves fromthe raised position 230 to the lowered position 220, the indicatorsleeve 330 moves away from the indicator 340 to reveal progressivelymore of the indicator 340, which has indicia 341 (FIG. 9) thereoncorresponding to the position of the plug 80 within the seat 40.

The rotational drive mechanism 190 further preferably includes a thrustassembly 350 disposed about the drive shaft 210 that includes at leastone thrust bearing 360 to prevent axial movement of the drive shaft 210while facilitating rotational movement of the drive shaft 210 (FIG. 7).The drive shaft 210 preferably terminates at a top end 218 thereof witha nut 370, such that a handle wrench 380 or wheel (not shown) may beused to manually rotate the nut 370 to move the valve apparatus 10between the closed and open positions 120,130. Alternately, the driveshaft 210 terminates at a breakaway actuator coupling 400, such that anelectrically-driven valve actuator 410 engaged with the actuatorcoupling 400 may be used to remotely move the valve apparatus 10 betweenthe closed and open positions 120,130.

In use, the bonnet chamber 150 at the lower end 62 of the upper portion60 of the lower stem 50 is always in fluid communication with the inlet28 through the at least one top aperture 110 of the upper end 78 of thelower portion 70 of the lower stem 50, the conduit 90, and the at leastone plug aperture 100 of the plug 80, such that the fluid pressure atthe upper portion 60 of the lower stem 50 is substantially equal to thefluid pressure at the inlet 28. As such, the annular seal 170 preventsthe fluid from leaking between the upper portion 60 of the lower stem 50and the bore 160 of the bonnet 140. Further, but pressure of the atleast one annular seal 170 against the lower stem 50 accounts for mostof the friction that must be overcome for the rotational drive mechanism190 to move the plug 80 between the open and closed positions 130,120.

Example

A valve apparatus 10 identified as Prototype Choke AA200 Choke Assemblywith a 4-20 mA electric Bettis-brand Actuator 410, as heretoforedescribed, was tested for several days in August of 2013 at threedifferent pressures (5000 psi, 10,000 psi, and 14,000 psi), cycling thevalve a minimum of 160 times under pressure. The valve apparatus 10 wasinitially cycled 50 times at 5,000 psi, and resulting in a required 10.7ft-lbs of torque to close the valve, and 5.3 ft-lbs to open the valveapparatus 10. Next, a room temperature of 86-degrees F., at a pressureof 10,500 psi, the torque required to close the valve apparatus 10 was17.0 ft-lbs, and to open the valve apparatus 10 required 9.0 ft-lbs.Then, at a pressure of 14,000 psi, the torque required to close thevalve apparatus 10 was 23.3 ft-lbs, and to open the valve apparatus 10required 11.2 ft-lbs. All test checked good with no leaks. The valveapparatus 10 was cycled a total of 270 times with pressures up to 14,000psi. In one test with the electric actuator 410, at 5,000 psi the motordrew 1.2 amps to open and close the valve apparatus 10. AT 7,500 psi theactuator 410 required 1.6 amps to actuate the valve apparatus 10. At10,500 psi, the actuator 410 still only required 1.6 amps to actuate thevalve apparatus 10.

FIG. 10 illustrates a flow diagram of the actuated choke valve 10 usedfor the oil and gas well flow automation. The fluid enters in the inlet28 of the choke valve 10 at higher pressure from an adjoining gate valve(now shown), for example. The fluid passes through the outlet 29 of thechoke valve 10 depending upon the position of the plug 80 attached tothe lower stem 50. A command signal is initiated from a SCADA system,for example, based upon the requirement of the differential pressure ofthe outlet 29. From the required output of the well the orifice diameteris selected by the customer, through SCADA, and through the welloperator. The command signal is initiated from the master SCAD to alocal controller. The electric actuator starts to operate the chokevalve mechanism for the opening, in 64^(th) diameter increments. Oncethe required opening is reached the controller send the feedback signalto SCADA or local controller, completing a closed loop system. Thepressure is monitored at the output 29 to produce the required fluidflow. The trim position of the choke or plug 80 is changed by operatingthe choke valve 10 to achieve a required outlet pressure. Thus theactuated choke valve 10 is used for controlling, throttling, andmonitoring the flow from the well.

While a particular form of the invention has been illustrated anddescribed, it will be apparent that various modifications can be madewithout departing from the spirit and scope of the invention. Forexample, while a choke-type plug 80 and a cylindrical gate-type plug 250are illustrated, other types of valve plugs 80 could be utilized withthe present invention. Accordingly, it is not intended that theinvention be limited, except as by the appended claims.

Particular terminology used when describing certain features or aspectsof the invention should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects of the invention with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the invention to the specific embodimentsdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe invention encompasses not only the disclosed embodiments, but alsoall equivalent ways of practicing or implementing the invention.

The above detailed description of the embodiments of the invention isnot intended to be exhaustive or to limit the invention to the preciseform disclosed above or to the particular field of usage mentioned inthis disclosure. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. Also, the teachingsof the invention provided herein can be applied to other systems, notnecessarily the system described above. The elements and acts of thevarious embodiments described above can be combined to provide furtherembodiments.

All of the above patents and applications and other references,including any that may be listed in accompanying filing papers, areincorporated herein by reference. Aspects of the invention can bemodified, if necessary, to employ the systems, functions, and conceptsof the various references described above to provide yet furtherembodiments of the invention.

Changes can be made to the invention in light of the above “DetailedDescription.” While the above description details certain embodiments ofthe invention and describes the best mode contemplated, no matter howdetailed the above appears in text, the invention can be practiced inmany ways. Therefore, implementation details may vary considerably whilestill being encompassed by the invention disclosed herein. As notedabove, particular terminology used when describing certain features oraspects of the invention should not be taken to imply that theterminology is being redefined herein to be restricted to any specificcharacteristics, features, or aspects of the invention with which thatterminology is associated.

While certain aspects of the invention are presented below in certainclaim forms, the inventor contemplates the various aspects of theinvention in any number of claim forms. Accordingly, the inventorreserves the right to add additional claims after filing the applicationto pursue such additional claim forms for other aspects of theinvention.

What is claimed is:
 1. A choke valve apparatus for controlling the flowof fluid between a source and a receiver, comprising: a choke valve bodyhaving a choke valve chamber with an inlet and an outlet; a seatdisposed within the choke valve chamber; a lower stem having an upperportion and a lower portion, the lower portion having an upper end and alower end and terminating at the lower end thereof with a plug, aconduit traversing the lower portion between at least one plug aperturetraversing the plug to at least one top aperture traversing the upperend of the lower portion, the lower portion slidably retained at leastpartially within the choke valve chamber between a closed positionwherein the plug abuts the seat to prevent fluid flow between the inletand the outlet, and an open position wherein the plug is axiallyretracted from the seat to permit fluid flow between the inlet and theoutlet, the conduit venting the choke valve chamber in the closedposition; a bonnet selectively fixed with the choke valve body andhaving a bonnet chamber axially aligned with the lower portion forreceiving the lower portion at least partially and slidably therein, thebonnet including a bore axially aligned with the lower portion, the boreincluding at least one annular seal, the conduit comprising a flowpathhaving openings only at the top aperture positioned within the bonnetchamber and the at least one plug aperture; the upper portion of thelower stem axially aligned with and fixed at a lower end thereof withthe upper end of the lower portion, the upper portion slidably retainedwithin the bore of the bonnet and the annular seal, the upper portionbeing at most one-half of the diameter of the lower portion; and a yokeassembly selectively fixed at a lower end thereof with the bonnet andterminating at an upper end thereof with a rotational drive mechanism,the yoke assembly including an upper stem axially aligned with the lowerstem and having a threaded upper end and a lower end fixed with theupper end of the upper portion of the lower stem, the rotational drivemechanism including an internally-threaded rotational drive shaft thatcaptures and drives the threaded upper end of the upper stem between araised position corresponding with the open position of the plug andlowered position corresponding to the closed position of the plug;whereby the bonnet chamber at the lower end of the upper portion of thelower stem is always in fluid communication with the inlet through theat least one top aperture of the upper end of the lower portion, theconduit, and the at least one plug aperture such that the fluid pressureat the upper portion of the lower stem in substantially equal to thefluid pressure at the inlet, the annular seal preventing the fluid fromleaking between the upper portion of the lower stem and the bore of thebonnet.
 2. The choke valve apparatus of claim 1 wherein the plug is agenerally conical choke-type plug.
 3. The choke valve apparatus of claim2 wherein the plug and seat are both made from a relatively hard carbidematerial embedded in a jacket comprised of a nickel or chrome-basedmaterial.
 4. The choke valve apparatus of claim 1 wherein the plug is agenerally cylindrical gate-type plug.
 5. The choke valve apparatus ofclaim 4 wherein the plug and seat are both made from a relatively hardcarbide material embedded in a jacket comprised of a nickel orchrome-based material.
 6. The choke valve apparatus of claim 1 whereinthe lower portion of the lower stem is axially maintained within thechoke valve chamber with at least one annular U-ring situated betweenthe at least one top aperture and the at least one plug aperture.
 7. Thechoke valve apparatus of claim 1 wherein the bonnet is selectively fixedwith a threaded portion of the choke valve body at a metal-to-metal sealby a wing nut, the metal-to-metal seal preventing the fluid from leakingbetween the choke valve body and the bonnet when the wing nut istightened.
 8. The choke valve apparatus of claim 1 wherein the bore ofthe bonnet further including a threaded, annular packing nut throughwhich the upper portion of the lower stem is slidably retained, the boreincluding a packing nut thread for engaging the packing nut, whereby theannular seal may be accessed and lubricated from outside of the bonnetby removing the packing nut.
 9. The choke valve apparatus of claim 1wherein a yoke assembly is selectively fixed with a top side of thebonnet at a yoke support plate of the bonnet.
 10. The choke valveapparatus of claim 1 wherein the yoke assembly includes a yoke having atleast one slot therein aligned with the upper and lower stems, the atleast one slot adapted for slidably capturing a shoulder bolt therein,the shoulder bolt transversely engaged with the upper and lower stems toprevent rotation of the upper and lower stems by the drive shaft,whereby rotary motion is converted to linear motion.
 11. The choke valveapparatus of claim 10 wherein the yoke assembly further includes anouter indicator sleeve fixed with the upper stem and an inner indicatorfixed with the yoke assembly and within the indicator sleeve, whereby asthe upper stem moves from the raised position to the lowered positionthe indicator sleeve moves away from the indicator to revealprogressively more of the indicator, the indicator having indiciathereon corresponding to the position of the plug within the seat. 12.The choke valve apparatus of claim 1 wherein the rotational drivemechanism further includes a thrust assembly disposed about the driveshaft that includes at least one thrust bearing to prevent axialmovement of the drive shaft while facilitating rotational movement ofthe drive shaft.
 13. The choke valve apparatus of claim 12 wherein thedrive shaft terminates at a top end thereof with a nut, whereby a handlewrench or wheel may be used to rotate the nut to move the choke valveapparatus between the closed and open positions.
 14. The choke valveapparatus of claim 12 wherein the drive shaft terminates at an actuatorcoupling, whereby an electrically-driven choke valve actuator engagedwith the actuator coupling may be used to remotely move the choke valveapparatus between the closed and open positions.
 15. The choke valveapparatus of claim 1 wherein the lower end of the upper stem isselectively fixed with the upper end of the upper portion of the lowerstem at a coupler.
 16. The choke valve apparatus of claim 1 wherein thechoke valve seat is selectively fixed within the choke valve body at ametal-to-metal seal by a treaded arrangement, the metal-to-metal sealpreventing the fluid from leaking between the choke valve seat and thechoke valve body when the choke valve seat is tightened within the chokevalve body.
 17. The choke valve apparatus of claim 1, further comprisinga breakaway coupler releasably joining the lower end of the upper stemwith the upper end of the upper portion of the lower stem, saidbreakaway coupler releasing the rotational drive mechanism at apreferred torque threshold limit.
 18. The choke valve apparatus of claim17, wherein the breakaway coupler comprises a frictional sleeve fixed tothe upper end of the upper portion of the lower stem, said frictionalsleeve having a frictional engagement limit corresponding to thepreferred torque threshold limit.